A new tricyclic alkaloid named portulacatone (1), i.e., 5,6-dihydro-8,9-dihydroxy-11H-pyrrolo[2,1-b] [3]benzazepin-11-one, together with eight known compounds, methyl 4-hydroxyphenylacetate (2), p-hydroxybenzaldehyde (3), vanillin (4), protocatechualdehyde (5), p-hydroxybenzoic acid (6), iseluxine (7), oleracein E (8), and (+)-(R)-feruloyl malate (9) were isolated from aerial parts of Portulaca oleracea L. Their structures were elucidated based on spectroscopic analyses. Among them, compounds 1–7 and 9 were isolated from this medicinal plant for the first time. Compounds 1 and 7 showed dose-dependent scavenging activities against DPPH (2,2-diphenyl-1-picryl-hydrazyl) free radical, with EC₅₀ values of 14.36 μM and 9.98 μM, respectively, more potent than the natural antioxidant vitamin C (EC₅₀ 20.72 μM).

Fourteen sesquiterpenoids were isolated from the fruits of Alpinia oxyphylla Miq. Their structures were elucidated based on NMR analyses (¹H, ¹³C, DEPT, ¹H,¹H-COSY, HMQC, HMBC, and NOESY) and identified as 12-nornootkaton-6-en-11-one (3), (+)-(3S,4aS,5R)-2,3,4,4a,5,6-hexahydro-3-isopropenyl-4a,5-dimethyl-1,7-naphthoquinone (5), nootkatene (6), 9β-hydroxynootkatone (7), 2β-hydroxy-δ-cadinol (8), 4-isopropyl-6-methyl-1-tetralone (11), oxyphyllone E (12), oxyphyllone D (13), oxyphyllanene B (15), oxyphyllone A (16), oxyphyllol E (17), (9E)-humulene-2,3;6,7-diepoxide (18), mustakone (20), and pubescone (21). Among them, 3 was a new norsesquiterpenoid, 8 was a new natural product, and 5, 6, 11, 20, 21 were isolated from A. oxyphylla for the first time. Twenty sesquiterpenoids, 1–5 and 7–21, were investigated for their in vitro acetylcholinesterase (AChE) inhibitory activities, including previously isolated seven sesquiterpenoids from A. oxyphylla, (11S)-12-chloronootkaton-11-ol (1), (11R)-12-chloronootkaton-11-ol (2), nootkatone (4), oxyphyllenodiol A (9), oxyphyllenodiol B (10), 7-epiteucrenone B (14), and alpinenone (19). TLC-Bioautographic assay indicated that 1–4, 7, 14, 16, 18, 19, and 21 displayed anti-AChE activities at 10 nmol. Microplate assay confirmed that 19, 18, 16, and 21 displayed moderate-to-weak anti-AChE activities at the concentration of 100 μM, and 19 was the most potent inhibitor with an IC₅₀ value of 81.6±3.5 μM. The presence of anti-AChE sesquiterpenoids in A. oxyphylla may partially support the traditional use of this fruit for the treatment of dementia.

Two new halogenated eremophilane-type sesquiterpenoids, (11S)- and (11R)-12-chloronootkaton-11-ol (1 and 2, resp.), together with five known sesquiterpenoids, nootkatone (3), 7-epiteucrenone B (4), oxyphyllenodiol A (5), oxyphyllenodiol B (6), and alpinenone (7), were isolated from the EtOH extract of the fruits of Alpinia oxyphylla Miq. The structures were elucidated based on the analyses of their spectroscopic data.

Two alkaloids, oleraceins F and G, were isolated from Portulaca oleracea L., and their structures were determined as methyl (2S)-6-[(β-D-glucopyranosyl)oxy]-2,3-dihydro-5-hydroxy-1-[(2E)-3-(4-hydroxy-3-methoxyphenyl)prop-2-enoyl]-1H-indole-2-carboxylate and methyl (2S)-6-[(β-D-glucopyranosyl)oxy]-2,3-dihydro-5-hydroxy-1-[(2E)-3-(4-hydroxyphenyl)prop-2-enoyl]-1H-indole-2-carboxylate, based on their spectroscopic data. Oleraceins F and G exhibited scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, with EC₅₀ values of 21.00 and 37.69 μM, respectively.

Because indoline is an important intermediate of angiotensin-converting enzyme (ACE) inhibitor and the antihypertensive drug “pentopril”, and also because it is a ubiquitous scaffold found in the structures of several naturally bioactive alkaloids such as vinblastine, strychnine, (–)-physostigmine, ajmaline, and (+)-aspidospermidine, the synthesis of this “privileged structure” is meaningful in the design of new biologically active medicines. This microreview describes the recent advances in the synthesis of indoline derivatives, including Cu- and Pd-catalyzed reactions, metal-free approaches (radical reaction), as well as other types of reactions.